Using ObjectSpace.define_finalizer

finalizer.rb

class Source
  def initialize(source_zip)
    @tmp_dir = Dir.mktmpdir
    ObjectSpace.define_finalizer(self, self.class.finalize(@tmp_dir))
    # Dump contents of zip into tmp dir
  end

  def self.finalize(tmp_dir)
    proc {FileUtils.rm_rf(tmp_dir)}
  end
end